Method and apparatus for multi-stage stabilization of whole grain flour

Abstract

The present invention relates a method and a system for a multi-stage treatment of whole grain flour to reduce enzyme activity, and more specifically, for the rapid treatment of whole grain flour to reduce the lipase enzyme activity for increasing shelf-life using microwave energy for at least one of the stages.

1 . A method of providing a whole-grain flour having reduced lipase enzyme activity using a multi-stage deactivation process, the method comprising:
 separating a flour fraction having endosperm from a bran fraction having bran and germ, the bran fraction having a lipase enzyme activity;   subjecting the bran fraction to a first treatment step effective to hydrate and to deactivate a first portion of the lipase enzyme activity to provide a hydrated bran fraction;   subjecting the hydrated bran fraction to a second treatment step using microwave energy effective to deactivate a second portion of the lipase enzyme activity to provide a treated bran fraction where the lipase enzyme activity in the treated bran fraction is reduced relative to the bran fraction by about 77 to about 100 percent;   combining the treated bran fraction with the separated flour fraction to provide a whole-grain flour having reduced lipase enzyme activity; and   wherein a total time of the combined first and second treatment steps is less than about 600 seconds.   
     
     
         2 . The method of  claim 1 , wherein the combining step includes combining about 68 to about 85 weight percent of the flour fraction with about 15 to about 32 weight percent treated of the bran fraction. 
     
     
         3 . The method of  claim 1 , wherein the first treatment step is a steam hydration of about 60 seconds to about 180 seconds to increase a moisture content of the hydrated bran fraction by about 25 to about 42 percent relative to the moisture content of the bran fraction. 
     
     
         4 . The method of  claim 1 , wherein the first treatment step is effective to reduce the lipase enzyme activity in the hydrated bran fraction relative to the bran fraction by about 20 to about 50 percent. 
     
     
         5 . The method of  claim 1 , wherein a moisture content of the hydrated bran fraction after the first treatment step is about 13 to about 20 percent. 
     
     
         6 . The method of  claim 1 , wherein the hydrated bran fraction consists essentially of particles having a size of about 200 to about 1000 μm. 
     
     
         7 . The method of  claim 1 , wherein the second treatment step uses microwave energy of about 5 kW to about 100 kW at about 915 MHz to about 20 GHz for about 60 to about 180 seconds. 
     
     
         8 . The methods of  claim 1 , wherein a ratio of a treatment time in the second treatment step to a treatment time in the first treatment is about 1:0.3 to about 1:3 and said ratio being effective to reduce the lipase enzyme activity in the treated bran fraction relative to the bran fraction by about 85 to about 100 percent when the total treatment time is less than about 360 seconds. 
     
     
         9 . The methods of  claim 1 , wherein a ratio of a treatment time in the second treatment step to a treatment time in the first treatment is about 1:1 to about 1:2.2 and said ratio being effective to reduce the lipase enzyme activity in the treated bran fraction relative to the bran fraction by about 90 to about 100 percent when the total treatment time is about 240 to about 360 seconds. 
     
     
         10 . The method of  claim 1 , wherein the second treatment step dries the moisture content of the treated bran fraction to about 5 to about 13 weight percent. 
     
     
         11 . The method of  claim 1 , further comprising processing the hydrated bran fraction to reduce a particle size of any agglomerates formed during the first treatment to about 200 to about 1000 μm. 
     
     
         12 . The method of  claim 1 , wherein the bran fraction and the hydrated bran fraction are treated at a bed depth of about 0.5 to about 3 cm during the first and second treatment steps. 
     
     
         13 . The method of  claim 1 , wherein the whole grain is selected from the group consisting of wheat, oat, barley, maize, rice, rye, spelt, millet, quinoa, triticale, amaranth, teff, corn, buckwheat, bulgar, sorghum and mixtures thereof. 
     
     
         14 . The method of  claim 13 , wherein the whole grain is wheat. 
     
     
         15 . The method of  claim 1 , wherein during the first treatment step the bran fraction is exposed to steam having a temperature of about 100 to about 150° C. and a pressure of about 2.4 to about 49 psi for about 60 to about 180 seconds. 
     
     
         16 . A method of providing a whole-grain flour having reduced lipase enzyme activity using a two-stage deactivation process, the method comprising:
 separating a flour fraction having endosperm from a bran fraction having bran and germ, the bran fraction having a lipase enzyme activity;   subjecting the bran fraction to a first deactivation step effective deactivate a first portion of the lipase enzyme activity;   subjecting the bran fraction to a second deactivation step effective to deactivate a second portion of the enzymatic activity and to provide a treated bran fraction; and   combining the treated bran fraction with the separated flour fraction to provide a whole-grain flour having reduced lipase enzyme activity, wherein the lipase enzyme activity in the treated bran fraction is reduced by about 77 to about 100 percent relative the lipase activity of the bran fraction.   
     
     
         17 . The method of  claim 16 , wherein the first deactivation step is effective to reduce the lipase enzyme activity about 20 to about 50 percent relative to the lipase activity of the bran fraction. 
     
     
         18 . The method of  claim 16 , wherein the first deactivation step is configured to deactivate the lipase enzymes from an outer portion of the bran fraction inwardly and the second deactivation step is configured to deactivate the lipase enzymes from an inner portion of the bran fraction outwardly to achieve the about 77 to about 100 percent deactivation in about 600 seconds or less. 
     
     
         19 . The method of  claim 16 , wherein the whole grain is selected from the group consisting of wheat, oat, barley, maize, rice, rye, spelt, millet, quinoa, triticale, amaranth, teff, corn, buckwheat, bulgar, sorghum and mixtures thereof. 
     
     
         20 . The method of  claim 19 , wherein the whole grain is wheat. 
     
     
         21 . A grain processing system configured to deactivate a lipase enzyme in a whole grain within a short amount of time, the system comprising:
 a hydration chamber arranged and configured to provide steam hydration effective to hydrate a milled bran fraction having both bran and germ and to deactivate at least a portion of a lipase enzyme activity in the bran fraction to form a hydrated bran fraction;   a microwave chamber after the hydration chamber arranged and configured to dry the hydrated bran fraction and to further deactivate the lipase enzyme activity in the hydrated bran fraction;   a breaking device positioned between the hydration chamber and the microwave chamber arranged and configured to break apart any agglomerates of the hydrated bran fraction that form in the hydration chamber;   a conveyor connecting the hydration chamber to the microwave chamber; and   the hydration chamber and microwave chamber configured to reduce the lipase enzyme activity by about 77 to about 100 percent relative the milled bran fraction in less than about 600 seconds.   
     
     
         22 . The grain processing system of  claim 21 , wherein the breaking device comprises a hopper having a wide opening at the hopper upper end for receiving the hydrated bran fraction into the hopper, a narrow opening at the hopper lower end for the hydrated bran fraction leaving the hopper, the profile of the hopper narrowing from top to bottom, and two rollers positioned within the hopper and in close proximity to each other such that the hydrated bran fraction passing through the hopper must pass between the rollers. 
     
     
         23 . The grain processing system of  claim 21 , wherein a ratio of a treatment time in the microwave chamber to a treatment time in the hydration chamber is about 1:0.3 to about 3:1 and said ratio being effective to reduce the lipase enzyme activity in the treated bran fraction relative to the bran fraction by about 85 to about 100 percent when the total treatment time is less than about 360 seconds. 
     
     
         24 . The grain processing system of  claim 21 , wherein a ratio of a treatment time in the microwave chamber to a treatment time in the hydration chamber is about 1:1 to about 1:2.2 and said ratio being effective to reduce the lipase enzyme activity in the treated bran fraction relative to the bran fraction by about 90 to about 100 percent when the total treatment time about 240 to about 360 seconds. 
     
     
         25 . The grain processing system of  claim 21 , wherein the conveyor comprises one or more conveyor belts connecting the hydration chamber to the microwave chamber.